I bought a 1.8L of unknown condition a few months back & decided to do a leakdown test on it before determining what to do with it.

Leakdown test was performed at 80PSI on a cold engine. Some leaks were detected at both valves in several cylinders. The valve leaks cleared up in each case by lightly tapping on the rocker arm...then the leakdown tests showed a tight engine.

My question is this:

Which results are valid...the leakdown numbers before or after tapping on the valves?

After.
A dormant engine sitting with the valves open can allow foreign material to accumulate
on the seating surface.
Anything (dust, soot)interfering with complete contact will permit leakage.
Tap on the valve or the rocker with the cylinder charged with compressed air.
If the engine has not been run for some time you'll probably see an immediate
increase.
BUT this is not the ultimate test of cylinder performance, it is only an approximation.
With this info the engine can now be run. Or not.
After cycling from cold to operating temp a few times a valid cylinder leakage test is possible.

Sounds as though there is some debris under the valves not allowing them to seal. I would to try to run it and I bet things will clear up

All cold/stored engines will have poor leak down numbers. Dirty valve seats, rings not seated. When your engine gets up to temp you should have great numbers. Best, Mark

I agree with the others.
If you are worried, pull the heads and lap the valves.

Thank you for the education gentlemen.

For what its worth,
I like to do my leak tests at 100psi.

It makes the math easier to figure percentage leak.

I've also always done it on a cold engine. I've also always kept a bottle of soapy water in a spray bottle to see where the air is leaking out externally. This will tell you if the case is collapsing, if you have bad head leaks, etc. But to do this you need the tins off, and the engine out of the car. So its hard to do this with an engine that has just run.

Zach

Listen at the tail pipe. If you hear anything it's an exhaust valve.
Listen at the throttle body.........................: it's an intake valve.
Listen at the oil filler neck..................................: it's the rings.

well said thats what I have always done ,I bought a 1.8 carb bus motor many years ago ,took a gamble as it didn't turn over fully ,this was a rush job as the owner wanted it gone that day but I wanted to run it otherwise no deal .
Pulled one head and found broken valve but little damage as it happened when the PO started it and he shut it down ,had a valve grind and new valve and put back together and it ran up fine but a bit rough as had been sitting for 3 yrs and the horrible Solex carbs were worn out.
Fitted it to my project and it just ran better every time I drove it , took it out and give it a good thrashing and it turned out to be the best $200 I every spent .
This proves that you can wake them up ,even as mentioned may only require valves reseating ,good luck to the OP , .

I brought a 1.6L Super Bettle back from the dead once.
Wife's worn-out beater that went over a year dormant once.

Actually, did a compression test on it. Most cylinders were 25 and the best was 40.

It wouldn't start on gasoline.
Even brand-new stuff...

I was positive it was gone.

It did start on B12 and I ran it for a bit on the 12.

Compression came back to the point it would run on the new fuel.

I drove the piss out of it for the next couple of hours.

At first its top speed was 20 mph and that steadily rose until it could run 60mph.

It came back fully over the next couple of weeks, and we drove it another three years...

I do leak downs at full operating temp (hard to re-create) as I normally see a 10% gain between hot and cold. Now, a bad leak down cold can often see engine problems.

I would not do a compression or leak down test on something that has sat for 6 months if it will start. The tests will not be accurate. Needs at least 1 hour of use UNDER LOAD if possible. Increasingly load is best. Powering up steep hills are what I try to use. I want midrange at full throttle if possible.

On a "unknown engine" I will do a "pulse" test just placing a finger over the plug hole. If you've got a dead one you can tell pretty quickly...

On an engine I'm building I'll do multiple leak down tests over the course of the build.
You can check cylinder sealing in two spots easily; TDC and BDC if the valvetrain is disconnected.

You will ALWAYS have a tiny bit of leakage at the valve seats. Filling the port with a liquid and doing a leak down will ALLWAYS show bubbles: hopefully they are tiny...